Optical hole film punch

ABSTRACT

A bed is provided having an aperture which is a female die with a light source below the aperture. A projecting microscope is mounted over the aperture and a marked film may be moved over the aperture so that an image of a place where a hole is to be punched is magnified on a screen. The film may then be clamped and a punch inserted through the aperture hole and punch a hole in an exact location on the film. This hole may then be used in conjunction with a guide pin to locate a second hole to thus provide two accurately located holes on the film. There may be two projectors located on a single base to enable larger magnification and to produce holes of different shape.

nited States Patent [1 91 Alilegian Get. 9, 1973 OPTICAL HOLE FILM PUNCH3,080,512 3/1963 Cubbidge et al 83/451 x [76] Inventor: Otto A.Ahlegian, 22570 Morton Avg. Fain/i6, park, Ohio 44 PrimaryExaminer-Andrew R. Juhasz Assistant Examiner-James F Coan [22] Ffled:1972 Attorney-J. D. Douglass [211 Appl. No.: 221,215

[57] ABSTRACT Cl 3/180 R, 33/1845, A bed is provided having an aperturewhich is a fe- 83/33, 83/35, 83/520, 83/688 male die with a light sourcebelow the aperture. A [51] Int. Cl B26d 7/ 16 projecting microscope ismounted over the aperture 5 8] Field of Search 83/33, 13, 520, 521, anda marked film may be moved over the aperture so 6 8 5, 8 R that an imageofa place where a hole is to be punched is magnified on a screen. Thefilm may then be [56] References Cited clamped and a punch insertedthrough the aperture UNITED STATES PATENTS hole and punch a hole in anexact location on the film. 3,290,975 12/1966 This hole may then be usedin conjunction with a 3353.339 5/1966 guide pin to locate a second holeto thus provide two 2,421,500 6/1947 accurately located holes on thefilm. There may be 3,368,439 2/ 1968 two projectors located on a singlebase to enable 3,492,900 2/ 1970 larger magnification and to produceholes of different 3,381,554 5/1968 Ploch et al 33/1845 X h 1,789,8511/1931 Vandercook et al. 83/521 1,800,209 4/1931 Christopherson 33/184.5 X 6 Claims, 5 Drawing Figures OPTICAL HOLE FILM PUNCH BACKGROUNDOF THE INVENTION It is highly desirable and sometimes a necessity thatit be possible to locate and punch holes in sheet material at exactlypredetermined places.

In the art of making printed circuits it is customary to make a sheet offilm on which the circuit design appears either in the form of anegative or a positive picture. Then a metal clad sheet of circuitboard, the surface of which has been photosensitized, is juxtaposed tothe film and light passed through the film onto the board to expose thesensitized surface which is then processed in one of the manners wellknown in the art to remove the portions of the metal cladding, which areundesirable, to leave the final conductive surfaces on the board.

One desideratum is that the actual board and the film have apredetermined fixed relation to each other so that the conductive designon the board is placed in predetermined exact points or positions on theboard. This is because the board may be subsequently used with automaticmachinery to apply circuit components, or, two or more boards may besuperimposed to construct the more complicated circuits. It is thereforeessential that the parts on the various boards be in proper registerwith each other in order to assure the proper electrical connectionsfrom one board to another.

Heretofore it has been the practice to take the film which is to be usedto make the printed circuit and punch two or more reference holes in thefilm at exact points relative to each other and to the circuit depictedthereon, then these holes are aligned with holes in the board, prior toexposure by suitable pins which pass through the board and film, whichthus causes the film to take an exact and always the same positionrelative to the board, after which exposure is made and then the twotaken apart and the board further processed. In order to obtain moreexact alignment of the board and film, the holes are usually placed asfar apart as possible, within the limits of the borders of the board.

In order to punch the holes in predetermined points, as determined bythe designer of the board, the position of the points may be determinedon the original draw ing of the circuit, which is subsequentlyphotographed to provide the film positive or negative, by a targetmarking which may be a small circle that is intersected by cross linesat right angles to each other, and which intersect each other at thecenter of the circle. These can be made to a high degree of accuracybecause the original design is usually made on an enlarged scale and,when photographed, is reduced to the size to be used on the boards.

DESCRIPTION OF THE PRIOR ART The film is then placed in an optical holefilm punch which consists of a base with a hole in it and a suitablelight source under the base whereby the light may be projected upwardthrough the hole. The hole may be a female die of the proper size forthe subsequent punching of the hole. Above the hole and also supportedby the base is a punch holder, the bottom of which is spaced above thebase sufficiently to allow the film sheet to he slid into the space.Sufficient clearance or throat space is provided that considerablelateral movement of the film in the throat may be had to permit thedesired positioning of the target markings. Above the punch holder andin alignment with the hole in the female die and base there is disposedan optical system, which includes a lens system together with a suitablemirror and translucent screen (which may be a ground glass type) wherebya suitable enlargement of the image on the film may be projected on thescreen in such a manner that the image is at a proper viewing angle forthe operator to readily see the enlarged view. This screen is accuratelymarked with calibration lines and with suitable indices coordinated withthe axis of the female die.

With the above the film may be inserted into the throat of the apparatusand moved around until the image of the target marking is in exactalignment with the calibration or cross hairs on the screen. Then a malepunch is inserted in the punch holder above the film and presseddownward to cause a hole to be punched in the film. The area of thethroat above the film and the spacing is such that although the film maybe moved to obtain registration, sufficient friction is applied toprevent accidental movement thereof and therefore once registration iseffected the hole will be in the exact desired place. If desiredauxiliary means may be provided to clamp the film and prevent movementthereof after registration has been effected.

As previously stated the punched holes are round holes and spaced aparton the film as far as reasonably possible in order to obtain more exactsubsequent uniformity of alignment, and were made independently of eachother.

The film, which is subject to expansion and contraction, presents aproblem in that if it happens to be expanded when placed over thecircuit board with reference pins, which are fixed distances apart andextend through the unexposed printed circuit board and film, tends tobuckle when brought into contact with the board. This leaves a spacebetween the film and the board which seriously affects the exposure andprevents the formation of sharp and well defined images thereon. If thefilm is in a contracted state, difficulty is experienced in placing thefilm over the reference pins and the film is either stretched to distortthe image or, as sometimes happens, torn at one of the reference holes.

SUMMARY OF THE INVENTION The present invention contemplates the punchingof the first hole as indicated above and then using that hole as a guidefor punching the second hole in exact relation to the first hole. Theexpansion and contraction problem is solved by making the second holeelongated so that exact lateral alignment of the two holes may beobtained and still permit a degree of expansion and contraction of thefilm between the holes and preventing buckling or stretching of thefilm. Because the one hole is round, at least one end of the film isalways held in exactly the same position. Additional accuracy may beobtained by punching the round hole in the approximate center of theboard and the expansion holes at approximate equal distances in oppositedirection but laterally exactly aligned to thus decrease the effect ofexpansion or contraction by one half.

A change is necessary in the apparatus to provide a second hole in thefemale die which is spaced from the first hole and wherein the secondhole is elongated. The punch guide must also have two guide holes whichnecessarily requires that the holes be but slightly spaced in order toprovide good guiding engagement for each male punch member and that anadditional male punch member with a punch part that matches the femalepart be provided. Preferably the elongated punch and die have roundedends that are of the same radius as the round punch and with anintermediate part of the same thickness as the diameter of the roundpunch. The distance between the ends of the hole may be approximatelytwice the diameter of the round punch and must be such that the maximumamount of expansion of the film will not cause the pins to engage withthe ends of the hole, taking into consideration the amount of expansionand contraction for the largest sheet of film to be processed. Althoughthe apparatus as noted above is highly satisfactory and is a greatimprovement over the prior art, there are certain limitations inherentin the arrangement which are overcome by another embodiment of theinvention.

One of the problems has been the limitations that the two stations, onefor punching round holes and the other for punching elongated holesplaces upon the optical system. It must be remembered that an extremelyhigh degree of accuracy of placement of the reference holes must bemaintained with the two punch type of apparatus. One problem has beenthe obtaining of sufficient magnification to allow accurate placement ofthe two holes and still enable the use of two punches which arenecessarily with their guide holes spaced apart at least the diameter ofthe punch body. Although the hole may be small, on the order ofone-eighth inch, the body of the punch may be as large as three-eighthsto one-half inch, therefore the field of view, which for greatestaccuracy should enable the reference to be aligned with the center ofthe optical system, must be made large enough to cover an area of nearly1 inch. Obviously only one of the two holes can be aligned with thecenter of the optical system, therefore both are placed equally spacedto one side of the center.

In addition to keep the price of such a device within a reasonable pricerange limitations are placed upon the magnification power of such asystem. Where one punch only is used it has been most practical toprovide a magnification of 20 times, although 31.25 or 50 times wouldenable even greater accuracy of alignment to be obtained. Although a 7binch field of view could be magnified as much as 40 times, with a twohole punch system and a field of 1 inch to be covered the result wouldbe an apparatus so large and cumbersome as well as extremely expensiveas to not justify the space or expense. For instance a 1 inch field ofview magnified 40X would take a screen 40 inches square.

Therefore it has been found that the expense and the space consumed canbe reduced to a very high degree and the magnification increased toprovide more accuracy by providing two optical systems whereby thegreater enlargement is obtained in each one and was heretoforeimpractical to carry out. The round holes are punched in one stationthen the film transferred to the other station and the elongated holepunched. The entire system taking less than twice as much room as asingle system and costing less than twice as much due to the fact thatcertain parts are common to each other.

BRIEF DESCRIPTION OF THE DRAWING In the drawing: FIG. 1, is a sideelevational view of the apparatus of the invention;

FIG. 2, is a front elevational view thereof;

FIG. 3, is an enlarged plan view of a fragment of the base plate showingthe light aperture and female die;

FIG. 4, is an enlarged elevational view of a punch;

FIG. 5, is a diagramatic view of an aperture and female die elementshowing a round and elongated hole female die.

DESCRIPTION OF THE PREFERRED EMBODIMENT In carrying out the invention, abase 10 is provided and an apparatus which comprises a first station ismounted on one side of the base and includes a heavy rigid pedestal 12attached to a base plate 14 which in turn is rigidly secured to thebase. Above the base 14 is smaller plate 16 which is spaced from theplate 14 to provide a throat 18 into which a film may be slipped. Thebase 14 supports a female die 20 below the plate 16 and in alignmentwith the optical system. A suitable light system indicated by the dottedcrossed square 22 is disposed in or below the base 10 arranged toproject rays of light upward through the female die and through the holein a punch guide 24 into the magnifying optical system. The opticalsystem may be conventional and include a lens tube 26 and a housing 28which houses a mirror and enables an image to be projected on a screen30.

With the light source 22 energized, the film to be punched is slippedinto the throat 18 and the image on the film projected onto the screen30. Exact alignment may be obtained because of the magnified image. Oncethe optical alignment has been obtained the film may be clamped in placeand a punch such as shown in FIG. 4 is used to punch the hole in thefilm.

As stated before the female die could have two holes in it as shown inFIG. 5 where the outline of the die 20a is shown and has a round diehole 20b and an elongated hole 20c but they must be spaced apart, moreor less as shown, in order to make room for the guide surface 20d withthe result that it is impractical to have them aligned with the centerof the optical system and the desired magnification is inhibited by thelarge screen necessary.

The punch includes a male punch member 32a which matches with the hole20b, and a body 32b from which the punch projects and which in turn issupported by a body 320 that is guided in the guide 24. A suitablehandle or knob 32d is provided for handling the punch thus making itunnecessary to touch the punch or guiding parts with the hands.

Therefore as can best be seen from FIG. 2 there is provided two opticalsystems mounted on the same base 10 to provide two stations with onedesigned to punch round holes and the other elongated holes. The secondsystem may be substantially the same as at the first station except thatan elongated punch and die are used and there is a difference in thebase that enables another phase of the invention to be carried out. Atthe second station the base 14 is provided with a groove or slot 40extending from the forward edge of the base back to the pedestal 12.This slot so placed that it is in alignment with the center of the diesystem and is wide enough to receive a reference pin which may beslidable therein. A plain slot is illustrated, but it could be ofinverted T shape to allow a headed pin to be used.

The two punches, as shown in FIG. 2, include a round punch 32 formatching with a round hole such as 20b,

and an elongated (crosswise) punch 32' for matching with a hole such asshown at 200, FIG. 5. The two punches are conveniently stored in astorage block 42 disposed between the two stations.

In operation the film is placed in the first station and after opticalalignment has been effected, held or clamped and a round hole ispunched. The clamping can be by magnetic means if desired. Then the filmis transferred to the second station and the round hole placed over aslidable pin 46 disposed in the slot 40. This base is sufficiently longthat the second reference point can be aligned with the optical systemwhile the film at the previously punched end is prevented from lateralmovement at that end by the pin in the slot 40 projecting through theround hole in the film sheet. The reference point on the film havingbeen properly located on the screen according to the screen marking, itis clamped and the film is punched with the elongated punch. By thissystem it will be noted that the second reference point may be morequickly moved into location because the pin and slot combination holdsthe film against lateral movement. Also, because the one end of the filmis held, there is positive assurance that the elongated hole will bepunched with its longer diameter exactly aligned with the diameter ofthe first hole and that there is no tendency of the elongated hole toslant, and therefore if expansion or contraction occurs the side wallsof the longer hole are tangent to the reference pin and lateralalignment is positively assured to an extremely high degree of accuracy.

The throat 18 is sufficiently deep that the round hole may be centrallylocated in the film and elongated holes punched on opposite sides.

Inasmuch as two stations are used, with two optical systems, it ispossible to obtain the larger image magnifications at each stationwithout the need of an inordinately large screen. This fact alone,although increasing the cost of a single optical system as usedconventionally in the past, is less than the cost of a system withlarger magnification because the base It) and the controls are common toboth stations. What is more important is the fact that largemagnification can be obtained on a screen of small size and it ischeaper to make two small systems than one large system. Finally itenables a more compact arrangement with easier viewing.

I claim:

1. An apparatus for punching guide holes in a sheet of film having animage of a printed circuit thereon to enable said film to be placed overguide pins extending in fixed relation to a circuit board to be exposedfor forming a printed circuit thereon and wherein said film has markingsthereon to indicate where said holes are to be punched which comprises:afirst station including a base, a light source below the base and saidbase being formed with an aperture for allowing light to passtherethrough and to guide a punch, a magnifying optical system disposedabove the base, and having a screen with markings thereon forcorrelating the image on the film with the markings on the screen, meansfor enabling said film to be disposed between said light source and saidoptical system for projecting an enlarged image of a marking where thehole is to be punched and a first punch means for insertion in and to beguided by said aperture for said light source, to punch a hole in thefilm, a second station disposed on said base, a second light sourcebelow the base, said base being formed with an aperture for passinglight from the second source through the base and for the reception of apunch, and a second magnifying optical system disposed above the baseand having a screen with markings thereon for correlating an image onthe film with the markings on the screen, means for enabling said filmto be disposed between the light source and said optical system forprojecting an enlarged image of a marking where a hole is to be punchedand a second punch means for insertion in and to be guided by the wallsof said aperture for punching a second hole in said film.

2. An apparatus as described in claim 1 wherein said base is formed withmeans for the reception of a slidable guide means, said guide means isengaged in the first punched hole to hold said film at the place wherethe hole has been punched against lateral movement.

3. An apparatus as described in claim 2 wherein said guide means extendsfrom a forward end of the base toward, and in diametrical alignment withsaid aperture.

4. An apparatus as described in claim 3 wherein said guide means is agroove in said base having parallel side walls and a pin is slidablydisposed in said groove and of the same diameter as the first punchedhole and said film is engaged with the first punched hole over said pin.

5. An apparatus as described in claim 4 wherein said first punch meansis a round punch for punching a round hole and said second punch meansis one for punching a hole having one diameter the same as the diameterof the first punch and a second diameter normal to the first diameterlarger than the diameter of the first punch.

6. An apparatus as described in claim 5 wherein the second diameter ofthe second punch is at least twice the length of its first diameter.

1. An apparatus for punching guide holes in a sheet of film having animage of a printed circuit thereon to enable said film to be placed overguide pins extending in fixed relation to a circuit board to be exposedfor forming a printed circuit thereon and wherein said film has markingsthereon to indicate where said holes are to be punched which comprises:a first station including a base, a light source below the base and saidbase being formed with an aperture for allowing light to passtherethrough and to guide a punch, a magnifying optical system disposedabove the base, and having a screen with markings thereon forcorrelating the image on the film with the markings on the screen, meansfor enabling said film to be disposed between said light source and saidoptical system for projecting an enlarged image of a marking where thehole is to be punched and a first punch means for insertion in and to beguided by said aperture for said light source, to punch a hole in thefilm, a second station disposed on said base, a second light sourcebelow the base, said base being formed with an aperture for passinglight from the second source through the base and for the reception of apunch, and a second magnifying optical system disposed above the baseand having a screen with markings thereon for correlating an image onthe film with the markings on the screen, means for enabling said filmto be disposed between the light source and said optical system forprojecting an enlarged image of a marking where a hole is to be punchedand a second punch means for insertion in and to be guided by the wallsof said aperture for punching a second hole in said film.
 2. Anapparatus as described in claim 1 wherein said base is formed with meansfor the reception of a slidable guide means, said guide means is engagedin the first punched hole to hold said film at the place where the holehas been punched against lateral movement.
 3. An apparatus as describedin claim 2 wherein said guide means extends from a forward end of thebase toward, and in diametrical alignment with said aperture.
 4. Anapparatus as described in claim 3 wherein said guide means is a groovein said base having parallel side walls and a pin is slidably disposedin said groove and of the same diameter as the first punched hole andsaid film is engaged with the first punched hole over said pin.
 5. Anapparatus as described in claim 4 wherein said first puNch means is around punch for punching a round hole and said second punch means is onefor punching a hole having one diameter the same as the diameter of thefirst punch and a second diameter normal to the first diameter largerthan the diameter of the first punch.
 6. An apparatus as described inclaim 5 wherein the second diameter of the second punch is at leasttwice the length of its first diameter.